SHORT TERM CREATINE LOADING WITHOUT WEIGHT GAIN IMPROVES SPRINT, 1
AGILITY AND LEG STRENGTH PERFORMANCE IN FEMALE FUTSAL PLAYERS 2
Summary 3
Objectives. Futsal game requires players to perform frequent bouts of high-intensity activity 4
with limited rest periods that are not sufficient for full recovery. Therefore, creatine 5
supplementation may enhance performance by improving recovery rate. Along with this, the 6
number of studies conducted to determine the effects of creatine on performance in the 7
females is scarce. Thus, the main aim of this study is to identify the effects of short-term 8
(7/day) creatine supplementation on leg strength, velocity and agility in young female futsal 9
players. 10
11
Equipment and methods. A total of thirty of young female futsal players (aged: 19.83±1.13 12
years) participated in the study which was designed as randomized and double-blind, on a 13
voluntary basis. Participants were randomly assigned either to Creatine (n=15) or Placebo 14
(n=15) group. Over 7 days, Creatine group received 0.25 g/kg/day micronized pure creatine 15
monohydrate (Creapure, Hardline Nutrition, Kavi Gıda Istanbul, Turkey) and placebo group 16
did not take any supplements, apart from maltodextrin (Fantomalt, Nutricia, United 17
Kingdom). Before and after 7 days of loading creatine supplementation, body weight, leg 18
strength, velocity and agility performance of the participants were determined. The data 19
obtained were analysed with ANCOVA statistical model. 20
21
Results. Creatine supplementation significantly improved 10m, 20m and 30m speed 22
performances (p<0.05), leg strength (p<0.05) and agility (p<0.05) in female futsal players. 23
Depending on the creatine loading, however, no significant change in body weight was 24
observed (p>0.05). The data obtained provide that 7 days low dose creatine supplementation 25
may be an effective approach for improving exercise capacity in female futsal players 26
without an associated increase in body weight. 27
Key words: Creatine, ergogenic aid, futsal, female, performance 28
29 30
LA CHARGE DE CRÉATINE À COURT TERME SANS GAIN DE POIDS AMÉLIORE 31
LA PERFORMANCE DU SPRINT, DE L'AGILITÉ ET DE LA RÉSISTANCE AUX 32
JAMBES CHEZ LES JOUEUSES FUTSAL FÉMININES 33
Résumé 34
Objectifs: Le jeu de futsal exige que les joueurs effectuent de fréquentes périodes d'activité 35
de haute intensité avec des périodes de repos limitées qui ne sont pas suffisantes pour une 36
récupération complète. Par conséquent, la supplémentation en créatine peut améliorer les 37
performances en améliorant le taux de récupération. Parallèlement à cela, le nombre d'études 38
menées pour déterminer les effets de la créatine sur la performance chez les femmes est rare. 39
Ainsi, le but principal de cette étude est d'identifier les effets de la supplémentation en 40
créatine à court terme (7/jour) sur puissance des jambes, la vélocité et l'agilité chez les jeunes 41
joueuses de futsal féminines. 42
43
Équipement et méthodes: Au total, une trentaine de jeunes joueuses de futsal (âgées de 44
19,83 ± 1,13 ans) ont participé à l'étude, conçue comme une étude randomisée et en double 45
aveugle, sur base volontaire. Les participants ont été assignés au hasard soit au groupe 46
Créatine (n = 15) ou au groupe Placebo (n = 15). Sur 7 jours, le groupe Créatine a reçu 0,25 g 47
/ kg / jour de monohydrate de créatine pure micronisée (Creapure, Hardline Nutrition, Kavi 48
Gida Istanbul, Turquie) et le groupe Placebo n'a pas pris de suppléments hormis la 49
maltodextrine (Fantomalt, Nutricia, Royaume-Uni). Avant et après 7 jours de chargement de 50
supplémentation en créatine, le poids corporel, la force des jambes, la vélocité et l'agilité des 51
participants ont été déterminés. Les données obtenues ont été analysées avec le modèle 52
statistique ANCOVA. 53
54
Résultats: La supplémentation en créatine a significativement amélioré les performances en 55
vitesse de 10m, 20m et 30m (p <0.05), la force des jambes (p <0.05) et l'agilité (p <0.05) 56
chez les joueuses de futsal. Cependant, en fonction de la charge en créatine, aucun 57
changement significatif du poids corporel n'a été observé (p> 0,05). Les données obtenues 58
indiquent qu'une supplémentation en créatine à faible dose de 7 jours peut être une approche 59
efficace pour améliorer la capacité d'exercice chez les joueuses féminines de futsal sans 60
augmentation associée du poids corporel. 61
Mots-clés: Créatine, aide ergogénique, futsal, féminines, performance 62
1. Introduction 63
In the last three decades, futsal game has reached an increasing popularity and also developed 64
so fast after its full accreditation by the Fédération Internationale de Football Association 65
(FIFA) in 1989. Similarly, studies conducted over futsal have been expanding and reached to 66
88 Pubmed publication in 2016 April from 52 in 2014 August (1). Futsal is an indoor model 67
of soccer with the high physical demands and consisting of 5 players in each team including a 68
goalkeeper. According to the futsal game motion-time analysis, it has been shown that futsal 69
has intermittent high-intensity movement features dominantly (2). Additionally, some 70
different features of futsal game, such as the smaller playing area, frequent and fast direction 71
changes, require quick decision making, which ensues repeated sprints and agility capacity as 72
crucial factor to improve in performance (1, 3, 4). On the other hand, from the biochemical 73
point of view, the creatine/phosphocreatine (PCr) system can supply phosphate to the cell to 74
compensate adenosine triphosphate (ATP) deficit during high-intensity workouts (5, 6). Due 75
to the aforementioned use of creatine phosphate during high-intensity exercises, Creatine 76
monohydrate (CrM) supplementation has become very popular particularly in soccer (7) and 77
some other team sports (8). Particularly, 7 days CrM loading has been shown to improve 78
sprint power, endurance, dribble and a vertical jump test (9) which have been using to 79
simulate the soccer game movements and exercises (7). Another short-term creatine (Cr) 80
loading study has been applied over 6 days and found improvements in agility and repeated 81
sprint performances in highly trained female soccer players (10). Along with this, some 82
studies found 7 days Cr supplementation with no effect on dribbling, agility (with and 83
without the ball) and sprint performance in male futsal players (11). To our knowledge, there 84
is only one study evaluating Cr loading on motor performance in female futsal players over 85
two weeks, where the possitive effect of Cr supplementation wingate anaerobic power, 86
capacity, 20 m sprint and, muscular power performance were demonstrated (12). So the aim 87
of this study is to assess effects of a short-term (7 days), low dose Cr loading on sprint 88
performance, leg strength and agility in elite female futsal players. The experimental exercise 89
tests used in this study were selected based on similar activity patterns with futsal game. 90 91 92 93 94 95 1
2. Materials and Methods 96
2.1 Participants 97
This study was conducted in the Department of Physical Education and Sport at Dumlupinar 98
University in Kutahya, Turkey. Thirty highly trained Turkish female futsal players (19.8 ± 99
1.14 years, 164.2 ± 6.47 cm, 56.2 ± 6.34 kg) from the same team voluntarily participated in 100
this study. A written consent was obtained from the subjects after they were thoroughly 101
informed of the purpose and potential risks of participating in the study. All experimental 102
tests and procedures were conducted according to the declaration of Helsinki and all 103
participants understood and signed an informed consent which was approved by the 104
university ethical board. All subjects were competing in the Turkish first division women 105
futsal league during the course of the study. They've had minimum continuous futsal training 106
background of 4.53±.83 yr of experience. None of the participating players was vegetarian or 107
ate unusually large quantities of meat. This study was performed in February, which was the 108
official league break period and no official game was played so. Only the subjects who had 109
never been supplemented with CrM/maltodextrin or had never used anabolic steroids, were 110
allowed to participate in this study to avoid unknown possible physiological adaptations. 111
2.2. Experimental Design 112
A double-blind, placebo-controlled, randomized design was used in this study. After the 113
baseline anthropometric measurements, the subjects were assigned to either a creatine group 114
(CrG n= 15) supplementation group or a placebo (PlG n= 15) group by using the online 115
research randomizer (https://www.randomizer.org/) website. All trials were performed 116
approximately at the same time of the day, between 14 pm to 16 pm. After that; 10m, 20m 117
and 30m sprints, agility and leg strength performance tests were applied, respectively. Five 118
minutes rest were given between each test. The same protocol was repeated after 7 days Cr 119
supplementation.Subjects were instructed to maintain their normal diet throughout the testing 120
period, to avoid food and drink in the hour before each trial. None of them declared using 121
dietary supplements for at least 2 months before the baseline. All of the subjects underwent 122
the same training schedules during the protocol and also they were familiarized with each 123
exercise testing protocol separately, moreover, during the previous season they had been 124
tested with the same testing procedures several times. 125
126
2.2.1. Supplementation Protocol 127
After pretreatment testing, subjects were divided into either CrG or PlG. None of the subjects 128
had ingested CrM, or any other dietary supplements before initiation of the study. CrG group 129
received 0.25 g/kg/day micronized pure CrM (Creapure, Hardline Nutrition, Kavi Gıda 130
Istanbul, Turkey) for 7 days. PlG group received 0.25 g/kg/ day maltodextrin (Fantomalt, 131
Nutricia, UK) for 7 days, which was matched with the Cr powder for taste and colour. The 132
supplement was equally divided into two for consuming in breakfast and dinner to avoid the 133
reduction in urinary creatinine excretion and increase in whole-body retention of Cr (13). 134
Subjects mixed their supplement with ~300 mL of a warm water before consuming. During 135
the course of the study, the subjects were asked to refrain from exhaustive physical activity, 136
caffeine and alcohol consumption for 24 hours prior to testing. 137
2.2.2 Anthropometric Measurements 138
Before and after the supplementation protocol was started applying, body height and body 139
weight of the participants was measured with a standard digital scale accurate to the nearest ± 140
1 mm (Holtain Ltd. U.K.) and scale accurate to the nearest 0.1 kg (Tanita TBF 401 A Japan), 141
respectively. All pre and post measurements were conducted at the approximately same time 142
of the day. 143
2.2.3. Leg Strength 144
The isometric leg strength of 30 subjects was measured using Takei (Takei Kiki Kogyo, 145
Tokyo, Japan) portable, back and lift dynamometer and results were saved as kg. All subjects 146
stood upright on the base of the dynamometer with their feet shoulder-width apart. They were 147
asked to bend their back slightly forward at the hips and to hold their head upright. In this 148
position, they were requested to look straight ahead. Then without bending their back, they 149
were asked to pull as hard as possible on the chain and try to straighten their legs, keeping 150
their arms straight. They pulled against the weight steadily (no jerky movements), keeping 151
the feet flat on the base of the dynamometer. The maximum performance was recorded when 152
their legs were almost straight at the end of the lift. The result from the dynamometer was 153
read after the test. Two attempts were given to the participants and the best score was 154
recorded. 155
156
2.2.4. Sprint Test 157
The sprint runs were performed in the indoor futsal court. After a standardized 15-min warm-158
up period that included low-intensity running, several accelerations runs, and stretching 159
exercises, both Cr and Pl group undertook a sprint running test consisting of three maximal 160
sprints of 10, 20, and 30 m with a 60-s rest period between each test. During the 60-s 161
recovery period, the subjects walked back to the starting line. The running time of the sprints 162
were recorded using Newtest Powertimer 300 photocells (Oulu, Finland). The photocell gates 163
were placed at 10 m, 20 m and 30 m. All distance was run twice and the best time was 164
recorded. 165
2.2.5. Agility Test 166
The Illinois agility test (IAT) was used to measure agility during sprints including direction 167
changes without stopping, and running at different angles. This measurement was conducted 168
using Newtest Powertimer 300-series photocells (Oulu, Finland). Participants performed two 169
trials of the agility test with five minutes recovery between trials. The best time of the two 170
trials was recorded to use for statistics. 171
2.2.6. Statistics Analysis 172
The statistical analyses were performed using the SPSS version 21.0 software package (SPSS 173
Inc., Chicago, IL, USA). Data are presented as mean ±SD. ANCOVA with baseline time 174
measurement serving as the covariate in order to test for group differences in agility, strength 175
and sprint tests after Cr supplementation was used to analyze the data. Statistical significance 176
was set at α ≤ 0.05. 177
3. Results 178
Total thirty female futsal players (age: 19.83±1.13 yrs, height: 164.20±6.47 cm, BW: 179
56.23±6.34 kg) agreed to participate in the study and they all completed the study. There 180
were no differences existed among groups at the beginning of the study in terms of age, BW, 181
height, body mass index and training background (Table 1; p>0.05). All subjects reported 182
adherence to the experimental protocol and completed ingestion of the supplement. The 183
results of performance tests applied in the study were demonstrated in Table 2. The results 184
obtained showed that short-term Cr supplementation had no significant effect on BW 185
(p>0.05; Table 2). Along with this, 7 days of Cr supplementation (0.25 g/kg/d) resulted in 186
increasing 10m, 20m, and 30m sprint performance in CrG compared with PlG (0.03; p<0.05, 187
0.30; p<0.05, 0.00; p<0.05, respectively; Figure 1, Table 2). 188
CrG showed statistically significant increase in leg strength when compared to their baseline 189
value (pre: 106.2±13.0 kg, post: 117.9±12.98 kg; p<0.05). Using baseline time measurement 190
serving as the covariate, CrG had higher leg strength compared with PlG’s post value (CrG 191
post: 106.2±13.0 kg, PlG post: 81.70±17.29 kg; p<0.05, Table 1, Figure 2). 192
193
After Cr supplementation loading, agility performance in CrG improved statistically 194
significant compared with both their baseline value (pre: 18.33±0.92 sec, post: 17.60±0.88 195
sec; p<0.05, Figure 3) and PlG post value (CrG post: 17.60±0.88 sec, PlG post: 16.72±0.34 sec; 196
p<0.05, Figure 3). 197
4. Discussion 198
The major findings of this study were that short-term CrM supplementation improved 199
multiple sprints, agility and leg strength performance in female futsal players following 7 200
days of loading without an associated increase in BW. Although direct measurement of 201
muscle Cr was not done, the reported compliance of subject to a proven Cr loading protocol 202
provides indirect support of the success of our supplementation protocol. While there is only 203
one study published so far where authors aimed to know the effect of long-term Cr 204
supplementation in female players (12), to our knowledge, we are the first to assess the 205
efficacy of short-term Cr supplementation on performance in female futsal players 206
performing a sports-specific activity. 207
The substantial results obtained in this study provide that Cr supplementation can be used by 208
female athletes to improve physical performance. Our results are consistent with other 209
existing studies on Cr supplementation, showing the ergogenic effect of Cr supplementation 210
on exercise performance (14-16). In a review prepared by Miny and et al. related to Cr 211
supplementation in soccer, it has been clearly suggested that Cr loading may be an effective 212
strategy to enhance performances including muscle strength, sprint, and vertical jump (17). 213
In this study, Cr supplementation significantly improved sprint performance in 10m, 20m, 214
and 30m. These results are similar to previous findings (8, 18, 19). Some groups have failed 215
to find improvements in the repeated sprint performance after Cr loading (20, 21). This 216
discrepancy may be attributed to the difference in the experimental design and the choice of 217
the performance outcome. The results obtained in this study showed that acute Cr 218
supplementation provides a potential benefit in energy provision during very short-term, 219
high-intensity exercise. This may be the reason of the increase in sprint performance after 220
loading Cr. In addition, another mechanism that should be emphasized here is that expected 221
increase in muscle PCr after loading Cr supplementation, which was shown in a study 222
conducted by Casey (22). This would have been an effect on sprint performance. In a detailed 223
consensus statement on Cr supplementation by Terjung and et al. (2000) demonstrated that an 224
increase in PCr ranging from 10–20% achieved by Cr supplementation may contribute to 225
improving performance during a 30-s sprint due to the 2.5–5% increase in energy supply 226
(18). These findings explain the improvements seen in sprint performance in this study after 227
loading Cr supplementation. 228
Agility performance test time was shorter in the CrG compared to both CrG baseline value 229
and PlG post after loading. These findings of improved performance in agility test are one of 230
the most important part of loading Cr supplementation when taking into account that futsal 231
players have to achieve high-intensity activity during the game. As being similar to our 232
finding, some studies reported an increase in agility test performance after Cr loading (10, 233
23). A study conducted by van Leemputte and et al., (1999) demonstrated that increase in 234
intracellular stores of PCr would lead to improved efficiency of sarcoplasmic Ca++-ATPase 235
activity and cross-bridge cycling, thereby decreasing the energy costs of human skeletal 236
muscle relaxation (24). As a result of these adaptations, power production by skeletal muscle 237
would increase and maximal high-intensity muscular contractions could be sustainable for a 238
greater period of time (24). According to this theory, mechanisms underlying these effects 239
would facilitate the rapid and repeated muscle actions required agility, leading to an enhanced 240
performance in agility performance (23). 241
Other physiological parameter measured after Cr supplementation was leg strength of the 242
participants. The results showed that Cr supplementation resulted in increasing in leg 243
strength. These results are consistent with those studies showing the effects of Cr on strength 244
(19, 23, 25). In a study conducted by Brose and et al. (2003), it was found efficacy of Cr on 245
strength (26). Another study conducted by Urbaski and et al., (1999) observed an increase in 246
maximal isometric leg strength following 7 days of Cr supplementation (25gr/kg/d) (27). 247
Wiroth and et al., (2001) showed an increase in maximal strength after 5 days of Cr loading 248
(19). After Cr loading, this observed increase can be attributed to increasing in the level of 249
PCr in muscle (28). This assumption was supported by a study where vastus lateralis muscle 250
taken, showing this expected increase in PCr after Cr loading (22). 251
With few exceptions including the current one, almost all studies so far conducted have 252
reported increases in BW of 0.5–3.0 kg after Cr supplementation (7, 8, 29-33), some studies 253
have not (34-38). Possible reason behind this discrepancy may be explained with different 254
loading protocols applied in a different population. It is well known that a possible 255
mechanism underlying the short-term Cr-induced increase in BW is associated with the 256
increases in water retention in the intramuscular space as a result of the cellular transport of 257
Cr with Na+ (39) or a creatine-stimulated increase in myofibrillar protein synthesis (40). 258
However, short-term Cr loading applied in the current one didn't cause an increase in BW in 259
this study as seen. This may be explained with the training during the supplementation, which 260
may have been too intense and high in volume to allow sufficient gain in BW. 261
6. Conclusion 262
Cr supplementation used by athletes engaged in multiple sprint events, such as soccer and 263
other team sports has become popular recently. Due to its specific characteristic, futsal 264
performance that contains high intensity and short-term movement without resting period, 265
can be improved by loading Cr. Additionally, the effect seen in football players after Cr 266
supplementation cannot be generalized to futsal players because of the difference between 267
football and futsal. Taking into account all of these, to our knowledge, we are the first to 268
show the effects of short-term (7-days) Cr supplementation on physical performance in 269
female futsal players. In conclusion, short-term Cr supplementation (0.25 gr/kg/d) is 270
effective for increasing performance in female futsal players following 7 days of loading 271
without an associated increase in BW. 272
Funding statement 273
This research did not receive any specific grant from funding agencies in the public, 274
commercial, or not-for-profit sectors. 275
276
Conflict of Interest 277
The authors declare that they have no competing interest. 278
279 280 281
Acknowledgments 282
Many thanks to participants of female futsal team members and the team trainer. Also, we 283
appreciate to Assoc. Prof. Dr. H.Husrev Turnagol and Assoc. Prof. Dr. S. Nazan Kosar for 284
their skilful reading of the manuscript. 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 8
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